Concrete mixer



Jan. 31, 1961 A. J. DUANY 2,969,962

CONCRETE MIXER Filed May 1, 1957 ANDRES J DUANV 3 Sheets-Sheet 1 Jan. 31, 1961 A, DUANY 2,969,962

CONCRETE MIXER Filed May 1, 1957 3 Sheets-Sheet 2 [N VENTOR. ANDRES L]; DuA/vv' ATTORNEX A. J. DUANY CONCRETE MIXER Jan. 31, 19 61 3 Sheets-Sheet 3 Filed May 1, 1957 INVENTOR. ANDRES J DUAN) 'rf q I I ATTORNEM United States Patent O f CONCRETE MIXER Andres J; Duany, Mir'amar, Havana, Cuba (Apartado 778, Santiago de Cuba) Filed May 1,f1957, Ser. No. 656,436

2 Claims. (Cl. 259-169) The present inventionprelates to a novel and improved concrete mixer which is especially adapted to operate with r and discharge concrete-mix of extremely high quality which is normally characterized by a resistance to. flow due to the low quantity of water contained thereinpor to a relatively high content of aggregate.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment ofv the invention, and together with the description, serve to explain the principles of the invention.

Of the drawings:

Figure l is, a fragmentary side elevation of a concrete mixing and conveying unit in accordance with the present invention;

H Figure 2 is an end elevation of the structure shown in Figure 1;

Figure 3 is a fragmentary vertical sectional view showing concrete-mix being discharged from the apparatus of Figures 1 and 2; V

Figure 4 is an end view, similar to that 'shownin Figure 2'but with certain parts removed; and

Figure 5 is a detailed sectional view showing the vibrating means and its mounting as used in the illustrative embodiment of the present invention.

In the mixing and discharge of concrete, the concrete mixes which are conventionally used contain a relatively large proportion of water, or have a relatively small quantity of aggregate contained in them and can flow without great difliculty, thereby enabling them to be?- handled and discharged from the mixing drum, or the rotary drum in which they are transported, without.particular difliculty. Such relatively fluid mixes are not of the best possible quality, and it has been found that concrete-mixes which are relatively rich in aggregate, or are,

of relatively low water content, produce a form of concrete which has greatly superior strength properties, and

a such a concrete is even further improved by being sub jected to a relatively high-frequency vibration of its mass afterit has been poured in place, thereby contributing not only to its increased strength, its uniformity and other desirable properties, but also insuring that the poured concrete completely fills and mold or other casting form, so that no defects result in the concrete structure. However, difficulties are often encountered in se-. curing complete discharge of the very stiff concrete from the transport mixers, and it has often been necessary to place the chutes on steep inclines to avoid clogging or thenecessity of pushing the concrete along byhand,

eitherrnethod, being, accompanied by many incon-;

2,959,962 Patented Jan. 31, 1961 ice veniences and disadvantages, As a result it has sometimes been necessary to handle such'very stifigconcrete especially adapts it to handle concrete-mixes which are so stifi that they cannot be handled by conventional equipment, or without the provision of excessively steep chutes, buggies or buckets, and which also delivers a concrete-mix which flows with' relative ease and which avoids. the poor quality of concrete which results from an insufficient amount of aggregate or from an excessive amount of water, and which also delivers a concretemix which, in most instances does not require additional vibration once it has been placed in the form. A further object is the provision of a simple concrete mixer which is provided with a' discharge outlet and is adapted to deliver a readily flowing mass of normally stifi'concr'ete mix, which retains its fluidity for a considerable period of time, long enough to enable it to be transported to the form to which it is ultimately delivered. Still another object is the provision of a concrete-mixer which is generally of conventional construction, but which is adapted to discharge a fluidized mass of a relatively stiff concrete-mix of high quality; which flows as though it included additional quantities of 'water' and which requires less hand labor in transporting the concrete-mix to the forms and in filling the forms In accordance with the present invention, the.coticrete mixer comprises a rotationally mounted drum, which is conveniently mounted on a motor, truck so that the concrete may be mixed or maintained in an agitated condition while it isbein'g transported to the building site. I a

In accordance with the present invention, the concrete mixer comprises a rotationally mounted dru'm which is conveniently mounted on a motor truck so mature-concrete may be transported to the building site and additionally mixed and discharged from the drum by rotation of the drum, the concrete-mix issuing from ano'pen mouth of the drum and being discharged into a chute positioned beneath the open mouth, so that the concretemix may be conveyed by gravity, usually to' the form, by conveyor chutes of relatively small slope. Adjacent to the open mouth of the rotatable drum and'adapted to lie in the path of the relatively stiff concrete mix' issuing from the mouth of the drum as the drum is rotated is a relatively high speed vibration generator whiclnis located sufiiciently close to the mouth of the drum that the vibration is transmitted back through, the mass of concrete to the concrete still within the mouth of the drum, thereby fluidizing the issuing mass of concrete and making it. more ready to flow, or enablingit-to flow along a much less steep chute than would be possible without the effect of the vibration. Withsuch a vibrator located closely adjacent tothe mouth of the drum, a much stiffer mass of concrete-mix may be contained within the drum, as the eflect of the vibration is eflective within the narrowest portion of the drum mouth to fluidize the concrete mix. In this way the concrete mass may be made stitTer than would otherwise be possible, or a relatively stiff mass may be discharged with greater speed than would otherwise be possible, and in either case, the concrete-mix delivered to the chute flows along the chute with more than usual ease, and theconcretemix retains its increased fluidity even after it has been operation is not unduly delayed;

7 As embodied, the vibrator comprises a mechanically actuated vibrator which is normally adapted to impart from 3600 to 4000 vibrations or more per minute to the .mass of flowing concrete mix, and preferably comprises a vibratory member positioned horizontallly across the .mass of concrete-mix as it issues from the mouth, the

vibrator generally being driven from motor means which ,also serve to drive the rotary drum, so that the vibrator is driven at a relatively high speed whenever the drum is rotated in its normal slow rotation. While the drum may be tilted on its axis to deliver the concrete-mix therefrom it is preferably of the type in which the internal surface of the drum is provided with a screw so that rotation of the drum forces the concrete-mix from the drum even though the drum remains on a fixed and slightly upwardly inclined axis.

1 It will be understood that the foregoing general description and the following detailed description as well are exemplary and explanatory of the invention but are not restrictive thereof.

Referring now in detail to the present preferred and illustrative embodiment of the invention as shown in the accompanying drawings, there is provided a concrete mixing or conveying drum which may conveniently be constructed generally in accordance with the disclosure of the prior patent to Lendved No. 2,696,371 and comprises a conical drum 10 having a generally circular open mouth 12 at its rear and upper end, the interior of the drum being provided with one or more Archirnedean screw members or helical vanes 14 which are adapted to work the concrete mix upwardly and rearwardly of the drum in spite of its upwardly and rearwardly inclined axis. Drum 10 is rotatably mounted,

land at its rear end is supported by means of a circular tire 16 on a pair of trunnion rollers 18 freely rotatable in frame supports 20. Drum 10 is adapted to be rotated at will at a relatively slow speed such as or revolutions per minute, by means of a motor 22, such as a hydraulic motor, geared to the drum 10 by means of the motor sprocket 24, the chain 26 and the sprocket 28 mounted exteriorly on the smaller portion of the drum 10, and is adapted to be put into operation by means of a clutch member actuated by movement of the clutch lever 30.

Drum :10 is adapted to be loaded with a charge of concrete-mix through a loading chute 34 which is mounted on frame members 20 and has its lower end adapted to discharge the loaded material into the open end 12 of the drum 10.

When drum 10 is rotated in a counterclockwise direction (looking from the rear of the drum) the concretemix contained within the mixing drum is worked towards the rear of the drum and issues therefrom dropping by' gravity into the upper end of the inclined chute 36 which leads it to the form to be filled, or to a suitable conveyor bucket or wheelbarrow.

If very stiff mixes of concrete were to be contained within the drum 10, the mouth 12 of the drum would clog, and such material as did protrude from the mouth of the drum 10 would rotate with the drum, portions of A it gradually dropping to the upper end of the chute 36 and resting near the upper end thereof. this would indicate that the concrete-mix was too stilf to be handled, and either additional water would be added conventionally,

to the mix, or the mix would be laboriously pushed out of the mouth 12 into the chute 36 and along the chute,

after which additional complications would be encountered in filling the form with such a stiff concrete.

,from the mouth 12 as the drum 10 is rotated. These vibratory means preferably comprise an eccentrically loaded, elongated member rotatable within a non-rotating tubular member, and with the rotary member driven at a relatively high speed so as to cause the tubular casing to vibrate rapidly. Such exemplary structures are shown in the prior patents to Mall, Nos. 2,148,765 and 2,167,987.

Positioned horizontally of the concrete mixing drum and normal to the axis thereof, just below and slightly to the rear thereof, in the preferred form of the present invention, is a vibratory tube 40, the tube enclosing the rotary eccentrically-loaded vibration-producing member which is driven by means of the flexible shaft 44 from motor 22 by means of the bevel gearing 46 so that the vibratory movement of the tube 40 is many times as fast as the rotation of the drum 10, both being driven, in the preferred form from the same motor 22.

As embodied, the horizontal tube for generating the vibrations within the mass of issuing concrete mix, is mounted at its ends in relsilient supports as by being mounted in sheet rubber members 50 fixed to the supports 52 which extend from the upright frame members 20 at either side of the drum mouth 12. As shown in Figure 3 the vibratory member extends horizontally with the flowing mass of concrete-mix 58 as it issues from the mouth 12 of the drum 10.

Vibratory tube 40 is supported at its ends in the sheet rubber members, and for this purpose, one end of the tube 40 is provided with a non-rotary threaded stud 60 which projects from the end of the tube through a washer 62 and is clamped to the rubber sheet 50 by means of the collar 64, nuts 66 and jamb nut 68, the

nuts being held secure by means of a cotter pin 70 passing through the stud-end.

Near its other end, the vibratory tube 40 is supported in that rubber sheet 50 by means of a clamping flange 76 which is compressed within a suitable aperture in the rubber sheet and provides a central aperture which snugly fits the tube 40.

As so mounted, the vibratory tube 40 is resiliently supported and can easily move in any direction normal to its axial length, and consequently is adapted to impart a rapid vibratory movement to the flowing mass of concrete-mix as the concrete-mix is discharged over the tube in passing to the receiving trough 36.

The vibratory member preferably vibrates in excess of'about 1000 cycles per minute, and with this or more rapid rates of vibration the stiff mass of concrete within the drum 10 is fluidized not only in the area immediately. adjacent to the tube 40, but also upwardly and into the mass within the mouth 12, and the mass retains its fluid character fora considerable period of time so that it flows easily on low sloped chutes and is well adapted to flow easily into and fill the forms into which the concrete-mix is poured, retaining all of the advantages which can be expected from a concrete-mix which contains a relatively small amount of water or a relatively large amount of aggregate.

As illustrative of the many different relatively stiff forms of concrete-mixes which are suitable for use with the present invention, the following typical mix is given:

Crushed rock cubic feet-.. 27 Sand do 11 Cement do 6 Water gallons 30 to 33 able distance, so that the mass of concrete-mix at and near the mouth 12 of the drum is rendered relatively fluid and there is no tendency of the mix to block the mouth 12. Also, the concrete-mix retains its fluid character for a considerable period of time, so that even after the mix has been discharged from the lower end of the chute 36 there is ample time allowed for the mix to flow along the chute 36 and even to level itself as it fills the form into which it is later poured, and in which it is eventually to harden into a solid mass of concrete.

When the entire contents ofthe drum have been discharged, the clutch member 30 is moved to its neutral position, after which the power may be shut 011, and the drum is thereby prepared to receive another load of ingredients for the concrete mix.

In the operation of the concrete mixer of the present invention, as illustratively embodied in the form shown in the accompanying drawings, the ingredients of the relatively stifi concrete-mix are loaded into the concrete mixing drum 10 which is then rotated in a clockwise direction, looking from the rear, or as shown in Figures 2 and 4, and after a suitable period of rotation, the concrete-mix is thoroughly mixed, the Archimedean screw 14 having served to keep the concrete-mix from being fed from the open rear end 12 of the drum 10. When sufliciently mixed, and when it is desired to discharge the concrete-mix from the drum 10, as when the load of concrete-mix has reached its destination, the clutch lever 30 is moved to its discharge position, thereby reversing the direction of rotation of the drum 10 and causing the Archimedean screw means 14 to move the concrete-mix towards the open end 12 of the drum and towards the upper end of the chute 36. As the concrete-mix begins to issue from the open end 12, it comes in contact with the vibrating means 40 which imparts its vibratory motion to the mass of viscid concrete mix, thereby fluidizing the concrete-mix and allowing it to drop into the upper end of the chute 36 whereby it is conveyed into a wheelbarrow, or into the form in which the concrete-mix is to be allowed to harden.

The invention in its broader aspects is not limited to the specific mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

What is claimed is:

1. A concrete mixer comprising a rotatable drum to contain and discharge a mass of relatively stiff concretemix, said drum being provided with means for rotating it on a fixed axis upwardly directed towards a discharge mouth of reduced size, said mouth being associated with the drum so as to partake of the rotary motion thereof, means comprising helical vanes within the drum to force the mix through said mouth as the drum is rotated in one direction, a high-speed vibratory member closely adjacent the exterior of the mouth of said drum and extending substantially transversely with respect to the direction of flow of the mass of concretemix issuing from the mouth and positioned to lie within the mass of concrete-mix as it is forced from said mouth, a common drive means for rotating the drum and for vibrating said member, whereby the concrete-mix issuing from the mouth and within the drum immediately adjacent the mouth is fluidized allowing it to be flowed to its point of use.

2. The concrete mixer of claim 1 wherein said vibratory member is positioned horizontally of the drum and normal to the axis thereof and comprises an eccentrically loaded rotary member within a non-rotatable tubu- References Cited in the file of this patent UNITED STATES PATENTS 2,101,031 Little Dec. 7, 1937 2,185,540 Cady Ian. 2, 1940 2,254,448 Pursel Sept. 2, 1941 2,551,984 Walton May 8, 1951 

